Fungi are single-celled or multicelled organisms that must get their nutrients from other organic material.
- Some fungi live in water (Chytridiomycota), where they can give fungal infections to frogs and other aquatic creatures.
- Some eat decaying plants or animals, becoming the mold that grows on human food (Zygomycota). Mold on bread and baked goods comes from this family of fungi, as does the molds used to make many kinds of cheeses.
- Fungi in the Ascomycota family, including many kinds of yeast, are particularly toxic to humans and can cause conditions including athlete’s foot, ergotism (which can lead to hallucinations and convulsions), and ringworm. Some of these yeasts live in the human body, including Candida albicans, which can be triggered into excessive growth that causes yeast infections and candidiasis—a potentially fatal infection.
- Other fungi provide benefits to humans and plants. Glomeromycota gain nutrition from plants and transform plant sugar into minerals that they deposit into the earth, thus nurturing the plants from which they get their food.
- Basidiomycota include mushrooms and truffles—some of which are quite edible and beneficial, while others are poisonous.
The medical community has seen a recent rise in the number of fungal infections in patients, in large part because of systemic conditions that suppress the immune system. New drug therapies often treat the illness without curbing the accompanying fungal infection, and doctors sometimes do not detect the infection until it becomes life threatening. Fungal infections can affect agriculture as well, with significant losses of entire crops to microbial diseases—for example, the green mold Fusarium graminearum attacked the U.S. wheat crop between 1998 and 2000, causing an estimated loss of $2.7 billion to the wheat industry.
With so much loss of life and livelihood, experts in the fields of medicine and agriculture have spent considerable time searching for solutions to the fungus problem—one that will not cause further harm to the patient or spread toxic pesticides on cropland. One potential answer may be forthcoming through research on the antifungal effects of some essential oils.
Researchers have selected several oils on which to focus their efforts: thyme essential oil for its concentrations of thymol and carvacrol, two known antimicrobial components; tea tree oil, loaded with terpenes that kill fungi; peppermint essential oil; and clove essential oil. Another cluster of studies looked at the benefits of myrrh essential oil against topical fungi on the skin.
Pattnaik’s study in 1996 (see question 15: What is an antibacterial essential oil, and which essential oils have this property?) confirmed that aegle, citronella, geranium, lemongrass, orange, palmarosa, and patchouli essential oils all inhibited the growth of 12 different fungi, while eucalyptus and peppermint oils discouraged 11 of these fungi. When he broke the oils down into their constituents in a subsequent study, Pattnaik found that citral and geraniol were the specific factors in the essential oils that prevented the fungi’s growth. Linalool was nearly as effective as citral and geraniol, while cineole and menthol inhibited just 7 of the 12 fungi.
A study published in the Journal of Medical Microbiology (Pinto et al., 2006) examined the effects of a specific thyme essential oil, Thymus pulegioides (lemon thyme or broad-leafed thyme), on fungi including several strains of Candida, aspergillus (which causes the lung infection aspergillosis), and dermatophytes, fungi that cause infections of the skin, scalp, and nails. The thyme oil showed “significant activity” against the fungi in a laboratory, “deserving further investigation for clinical applications.” A 2010 study by Vale-Silva et al., published in the German journal Planta Medica, found even stronger results in applying thyme essential oil (T. viciosoi) to several fungi in a lab, observing “rapid metabolic arrest, disruption of the plasma membrane and consequently cell death.” This ability to break down the cell’s outer coating and destroy the cell appears to make thyme essential oil particularly effective in neutralizing fungal infections.
Calendula essential oil also appears to have strong antifungal properties, according to several studies. The Brazilian Journal of Microbiology published a study (Gazim et al., 2008) that found Calendula officinalis to have strong potential antifungal activity when tested against 23 fungi. A study published in the Journal of Environmental Science and Health (Císarová et al., 2016) concluded that clove, thyme, and oregano essential oils had the strongest effect on Aspergillus fungi of the 15 essential oils tested, though “all essential oils exhibited activity against all tested strains of fungi.”
The journal Scientia Pharmaceutica published a study in August 2020 that tested thyme essential oil from the T. vulgaris plant species to determine its effectiveness in treating topical inflammation and fungal infections. Boukhatem et al. (2020) found what others had discovered before them: a “potent anti-inflammatory effect at all doses.” Just two months later, in October, Frontiers in Cellular and Infection Microbiology published a paper (Parrish et al., 2020) in which the researchers detailed their study of 65 essential oils and 21 essential oil blends against a range of dermatophyte strains. Twenty-one days after treating the dermatophyte spores with the oils, the team found that cassia, cilantro, cinnamon, thyme, and oregano were the most effective against the fungi, as was doTerra’s proprietary DDR Prime blend, which contains clove, thyme, litsea, and wild orange essential oils.
A study published in Pharmaceutical Biology (Mahboubi and Kashani, 2016) analyzed the ability of myrrh extract and myrrh essential oil against dermatophytes in a laboratory. The researchers found that myrrh essential oil was more effective than the extract against topical fungus, leading them to conclude that their study “confirmed the traditional uses of C. molmol [myrrh] as a poultice for the treatment of cutaneous fungal infections.”
All these studies end with a call for more research. No pharmaceutical products have emerged to treat fungal infections with thyme essential oil, however, as the required phase II (mouse models) and phase III (human) studies have not been completed; moreover, until their publication, we have no way to know if they are even in progress. The common wisdom among companies that market essential oils is that thyme oil can remedy toenail fungus, one of the most stubborn conditions to treat, so the oil and various blends are available for this purpose. Some homeopathic products touted to treat topical fungi contain calendula essential oil, another one of the several that seem to be potent against these conditions.